Edexcel International

London Examinations

GCE Ordinary Level

Mark Scheme with Examiners’ Report

London Examinations Ordinary Level GCE in

Biology (7040)

January 2004

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April 2004

Order Code UO 014773

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N

BIOLOGY 7040, MARK SCHEME

Symbols used in the mark scheme

; indicates separate mark points/ indicates alternativeseq allow for correct equivalent

max maximum

Paper 1

1. (a) (i) use of an organism;to feed on/prey on/kill/ reduce numbers of a pest; (2)

(ii) suitable example of named ‘predator’;and named ‘pest’; (2)

(b) (i) reduces the amount of predation / prevents it being eaten/hunted eq; (1)

(ii) in the blood (stream) / circulatory / lymp(hatic) system; (1)

(c) lead to less photosynthesis;more carbon dioxide in atmosphere;less oxygen;more soil erosion / desertification / description of;less transpiration / rainfall;less food / disruption of food chain / extinction / less biodiversityX

(3 max)

(d) (i) metamorphosis; (1)

(ii) egg;tadpole;adult; any order (3)

(e) specific / does not affect other organisms;does not build up in food chains;does not pollute (the environment) / does not harm environment;pests do not become resistant;

(2 max)

(Total 15 marks)

O

2. (a) 72-58/72 X100 or 14 X72 X100; wrong fraction=019.4%;reduction / drop / minus sign given;(-19.4 = 3 marks) (19.4 = 2 marks) (minus ( - ) anything = 1 mark) (3 marks)

(ii) Heart volume becomes larger/ less beats to transfer same volume ofblood / each beat provides more blood; (1)

(b) heart volume increases;lung capacity / volume is unchanged; (2)

(c) lower resting heart rate therefore larger capacity to increase rate duringexercise;larger heart volume therefore more blood / oxygen / glucose (tomuscles);greater lung capacity therefore more oxygen (to muscles) / more carbondioxide removed ;ventilation rate is higher therefore more oxygen in / more carbon dioxideout;respiration can be aerobic therefore more energy released / less lacticacid accumulates; (4 max)

(Total 10 marks)

P

3. (a) FSH / follicle follicle development;stimulating hormone oestrogen release;

Oestrogen; inhibits FSH release;promotes LH release;Repairs / growth of uterus lining;develops secondary sexual characteristics / eg;

LH / luteinising promotes ovulation;hormone; develops / growth of corpus luteum;

promotes progesterone release;

Progesterone; inhibits FSH release;inhibits LH release;maintains / keeps uterus lining; (9 max)

(b) (i) testosterone; (1)

(ii) deep voice; Mark first two onlyfacial hair;body shape / more musclepubic / body hair;growth of reproductive organs;

(2)

(c) range GH treatment;same size / sex / species / age / strain etc;replication / more than 1 cow for each treatment ;measure mass / stated measurement eg height / girth;time – more than a month ;same control factor 1 e.g. place / environment / conditions/ housing;same control factor 2 eg food / temperature / water / lighting, etc; (6 max)

(d) (i) insulin;pancreas / islets of Langerhans;lowers blood glucose;(glucose) to glycogen;protein;digested; (3 max)

(ii) low - less respiration; lack of ATP / energy / tiredness; high - cells lose water / thirst / dehydration; by osmosis; damaged / crinkle /sticky / block blood vessels;

blood viscous /thickens / flows less easily / heart forced towork harder; =======

(4 max)

Q

4. (a) stamen;anther;filament;carpel;stigma;style;ovary;ovule;receptacle;petals / corolla / named petal;nectary;sepals /calyx: (7 max)

(b) pollination;pollen transferred to stigma;from anther;pollen grains germinates;pollen tube grows down style;enters ovule / micropyle;nuclei moves down pollen tube;male gamete / nucleus fuses with female gamete / nucleus / fertilisation;zygote formed;becomes embryo;endosperm formed / integuments become testa / seed coat;ovule becomes seed;

(8 max)

(c) same number of seeds;same strain / variety / genotype of seeds;same volume of water;same light conditions;method of temperature control;repeat for two stated temperatures;leave for stated days;medium for seeds / soil / cotton wool / paper etc ;count number germinated;

(6 max)

(d) water / moisture;allow chemical reactions /enzyme action / digestion;oxygen;allow respiration;light;to break dormancy;

(4)

R

5. (a) (i) carbon dioxide;water;chlorophyll;

(2)(ii) higher temperature;

enzymes work quicker;

higher carbon dioxide;

more light;

more photosynthesis ;more carbohydrate made;more respiration;

(3 max)

(b) Use of water plant;control 1temperature / mass of weed / availability of carbon dioxide etc;control 2method of collecting gas / count bubbles / measure volume;for stated time ;using two different light intensities;method of altering intensity / move lamp further away from plant (eq);expected results;

(7 max)

(c) (i) carbon hydrogen oxygen;

(ii) carbon hydrogen oxygen;

(iii) carbon hydrogen oxygen nitrogen (sulphur);

(1)

(1)

(1)

(d) in mouth food chewed / masticated / mixed with saliva / bolus formed;swallowed / moved by peristalsis;food churned / mixed by stomach;in small intestine / duodenum;bile added;neutralises stomach acid;provides suitable pH for enzyme action;emulsifies fat / forms tiny droplets;increases surface area for enzymes to act on;lipase;produced from pancreas / wall of small intestine;digests lipid into fatty acids and glycerol;absorbed into villi;villi increase surface area;carried in lacteal / lymphatic system ;

(10 max)

S

SK E~F= producers;primary consumers / herbivores;secondary consumers / carnivores;tertiary consumers;scavengers;decomposers / saprophytes / saprotrophsX

EQ=ã~ñF

EÄF= EáF= breakdown / digest / decompose / decay / recycle; (ignore ‘feed’)dead / non living/organic material; into inorganic / minerals / salts / elements / nutrients;

== ============(PF

EááF= hot + cold / range of temperatures;method of changing temperature eg incubator / oven / refrigerator;control 1;control 2;(eg same wetness / same bread etc)replication;measure area / diameter / radius / mass;time – one day to one weekX

ESF

EÅF= EáF= bacteria supplied with food or examples / warmth /moisture;digest / breakdown;cellulose /cell walls;enzyme / cellulase;glucose (for sheep);both organisms (bacteria + sheep) benefit; Allow once in (i) or (ii)

ERF===========================EááF

nitrogen-fixing / Rhizobium; supplied with glucose / minerals / vitamins / amino acids;

produce nitrates;needed for plant growth / amino acids / protein;both organisms (bacteria + plant) benefit; Allow once in (i) or (ii)

EPF

EÇF= named example eg Plasmodium;feeds on / off;host;named example of host; causes harm;

EQF

T

7. (a) (i) both down concentration gradient; both increase with increasing gradient; both increase with temperature;

(2 max)(ii) osmosis movement of water;

osmosis requires partially permeable membrane / diffusion doesnot; (2)

(b) (i) red blood cells;transport oxygen;haemoglobin;transport carbon dioxide;plasma;transports substance 1;transports substance 2;(carbon dioxide / hormones / glucose/ amino acids /fatty acids /glycerol / plasma proteins / antibodies / urea / salts / vitamins /cells )heat;

(6 max)(ii) white blood cells;

lymphocytes;produce antibodies / antitoxins;kill / destroy bacteria / viruses / pathogens;phagocytes / phagocytosis;engulf / eat / feed on bacteria / viruses / pathogens / foreignorganisms;platelets;clotting;prevent entry of pathogens;

(5 max)========Ec) large surface area to volume ratio;

short distance for diffusion; uses diffusion ;

(3) (d) potometer;

water tight / vaseline/ set up under water etc.; (cover with oil / etc) two humidity levels stated; method of varying humidity; movement of air bubble / column of water; leave for stated / record time; replication; control other factor eg temperature / light intensity/ same/ similar plant etc; expected results;

(7)

U

Paper 2

1. (a) A- trachea / larynx / voice box / windpipe;B- bronchus / bronchi;C- rib; (3)

(b) flat/ down/ lowered/ straightens eq; (ignore contracts/ stretched)relax;lowered / inwards / drops / downwards; (ignore ‘back to normal’/ not raised)more / high(er) ;low(er) / less; high(er) / more; (6)

(c) less/ no oxygen;less / no glucose;

less/ no respiration / less energy produced; (reject energy transported)

build up of carbon dioxide / no removal of carbon dioxide ;build up of lactic acid;fall in pH;enzymes denatured;

(3 max)

(Total 12 marks)

2. (a) three / C E G; (1)

(b) female;albino / white skinned; (ignore genotypes)

(2)

(c) square;half shaded; (ignore parents)

(2)

ProbabilityDescriptionzero 1/8 1/4 1/2 One

A and B having a childwith albinism

✔

D and P’s next child beinga girl

✔

D and P having a childwith albinism

✔

D and P having a femalechild with albinism

✔

EPF

Eqçí~ä=U=ã~êâëF

V

3. (a) (i) lines;points x 3;;;key / lines labelled; (5)

(ii) more ions absorbed with oxygen / group A;at a faster rate;correct reference. to figures; (3)

(iii) oxygen;(aerobic) respiration;energy available;active transport of ions; (3 max)

(b) No / less oxygen (to roots);no / less (aerobic) respiration;no / less absorption of minerals / active transport;roots (cells) die; (2 max)

(c) chlorophyll; (1)

(Total 14 marks)

QK= (a) B C F; (1)

(b) X;

osmosis / water moved out / plasmolysed;more water in cell / less water outside cell/ reference to water concentration.gradient/greater salt concentration outside / external solution has higher osmoticpotential / lower water potential;

=EPF

(Total 4 marks)

NM

5. (a) (i) glucose / oxygen; (ignore ammonia) (1)

(ii) carbon dioxide; (2)water;

(b) nitrogen; (1)

(c) temperature rise / overheated / eq;fungus killed / no or reduced growth;Enzymes denatured / destroyed;less mycoprotein / less SCP./.single cell protein / less fermentation; (3 max)

(d) A - nucleus;B - cell wall / chitin;C - cytoplasm;D - vacuole; (4)

(e) (i) (dietary) fibre; (1)

(ii) less energy;no / less animal fat;no / less cholesterol;(more )(dietary) fibre; (2 max)accept converse

(Total 14 marks)

6. (a) (i) carbon; (1)

(ii) photosynthesis;respiration;respiration;combustion / burning; (4)

(b) bacteria;fungi;saprobiont / saprotroph / saprophyte; (2 max)

(c) No / less plants / deforestation;No / less photosynthesis / process A;No /less carbon dioxide absorbed / more in environment;No / less respiration / process B;No / less carbon dioxide released / less in environmentX (3 max)

=====(Total 10 marks)

NN

7. (a) (i) 2 to 6 (years); (1)

(ii) 8 (years); (1)

(iii) young ones escape the net / not allowed to catch (illegal) /released after caught;small in size;

(2)

(iv) few old / big fish;less reproduction / laying of eggs; (2)

(b)Step Explanation

The water is kept oxygenated

aerobic;respiration;energy (for growth);

Faeces is removed from the water

stop decomposition / decay / break down;by bacteria /eq;prevent reduction of oxygen;prevent eutrophication;reject pollution / cleaning etc

Tanks containing the fish are covered with netsstop predators / birds eq;eating / removing fish;stop fish escaping;

2 max per box(6)

(Total 12 marks)

NO

8. (a) upper epidermis;palisade (mesophyll);spongy (mesophyll);lower epidermis; (4)

(b) (i) Qmore chloroplasts / chlorophyll;absorbs / traps more light;near upper surface / near light source / gets lots of light/ eq.; (3)

(c) xylem- transports water/ mineral ions;phloem- transports sucrose/ amino acids / translocation;(Ignore food / sugars /glucose)

(2)

(d) Letter Section numberP 4Q 3R 1S 2 (4)

(Total 13 marks)

9. (a) (i) A Mitosis mitotic;B Meiosis / meiotic; (2)

(ii) fertilisation / fusion; (1)

(b) spermegg

zygotewhite blood cell

red blood cell

23;23;46;46;0; (5)

(Total 8 marks)

10. (a) ticks in third, fourth and sixth boxes;( 4 ticks mark -1, 5/6 ticks zero)

(3)

(b) (i) glomerulus / (renal) capsule / (Bowman’s) capsule; (1)

(ii) first / proximal convoluted tubule ; (1)

(Total 5 marks)

NP

BIOLOGY 7040, CHIEF EXAMINER’S REPORT

PAPER 1

General Comments

The standard of performance of the candidates taking the examination was high with manycandidates scoring well across both papers. Few candidates encountered difficultyunderstanding the questions and there was little evidence of students running out of time oneither of the papers. The quality of English on the majority of scripts was good with only avery few candidates having difficulty making their responses clear. One feature that theexaminers commented upon this year was the improved response on the experimentaldesign items on the questions in Paper 1 Section B.

Section A

Question 1

This question required candidates to answer questions based on the printed passage usingtheir knowledge and understanding of biological facts and principles. Good candidates wereable to score well with marks of 13 or better being common.

(a) This part was generally answered well with even the weakest candidates scoring onemark for use of an organism. Some candidates did not earn the second mark as they did notspecify use of an organism to reduce the numbers of a pest. Most candidates were able togive appropriate examples of biological control correctly identifying both control organismand the pest species it is used to control.

(b) Most candidates were able to describe the effect of producing toxins and how this wouldreduce the amount of predation. A few candidates suggested that the toxin would pass toother organs by diffusion or by contact but most correctly suggested the circulation as themeans of transport.

(c) Many candidates were able to describe the effects of removal of vegetation as soilerosion and effect on the food supply. The best candidates were also able to describe thereduction in photosynthesis and the effects on the oxygen and carbon dioxide levels in theatmosphere.

(d) Almost all candidates identified metamorphosis and many also correctly listed egg,tadpole and adult.

(e) Candidates knew the advantages of using biological control such as it not affecting otherorganisms, not polluting the environment and not accumulating in food chains.

Question 2

This question required candidates to examine data on the effect of training on a malestudent using various physiological measures and a comparison with an internationalathlete.

(a) Although most of the candidates were able to calculate the percentage change in heartrate, very few earned full marks since they did not state or show that the change was adecrease or fall in heart rate. Candidates were able to suggest that the change in heart ratewas due to an increase in heart volume with the best candidates going on to describe howmore blood could therefore be pumped in each beat of the heart.

NQ

(b) This question was generally well answered with candidates noting the increase in heartvolume and that the lung capacity did not change.

(c) Several of the best candidates did not gain credit on this section because they failed tolink the difference in the measures shown in the table with benefits that the athlete wouldderive from these differences. For example the larger heart volume would provide moreoxygen and glucose to maintain respiration in the muscle tissue. Merely stating thedifferences in the measures without linking them to improved performance did not earncredit.

Section B

In this examination series, although a few of the weaker candidates failed to follow therubric, most answered three questions as instructed. The questions are designed to be ofthe same demand and each contains approximately the same number of marks requiringknowledge and understanding and requiring skills and processes. Candidates are gettingbetter at being able to describe experiments they could perform. Centres could helpcandidates by looking at past papers and encouraging students to practise such items.

Question 3

This was quite a popular question being answered by approximately 60% of candidates.

(a) Most candidates were able to name three hormones correctly but not all of thesecandidates were correctly able to assign functions to the named hormones. In particular therole of oestrogen in thickening the uterine lining and the role of progesterone in maintainingthe uterine lining were confused.

(b) Candidates were better at naming the male sex hormone testosterone and most couldgive two of the male secondary sexual characteristics, facial hair, body hair and deep voicebeing the most common answers.

(c) The weakest candidates did not attempt this part. This is a pity as the mark allocation forthis type of investigation credits the same points of experimental design as any laboratorystudy. So, as can be seen on the mark scheme, candidates should have chosen toinvestigate two groups of cows. These should be of the same age, sex, size, breed. Thecows should be weighed and their mass recorded. They should then be randomly assignedto two equal sized groups. One group of cows would receive a regular injection of GH, theother group no injection. The cows should be kept in the same conditions, the same sizedpens, the same amount and type of food, same water supply etc. The cows should be keptin these conditions for six months then reweighed and the percentage change in mass foreach cow determined. The mean values can then be calculated and the two groupscompared.

(d) Candidates were often able to identify the hormone as insulin and give its site ofproduction. They did less well at describing its effects and often merely gave its role ascontrolling blood glucose rather than lowering blood glucose if its level rose. Only a fewcandidates described the effect of low or high blood glucose, successfully explaining the lackof energy due to less respiration and the osmotic effects of high blood glucose leading todehydration and change in the blood viscosity.

NR

Question 4

This question was the least popular with approximately 25% of candidates answering it.However, those candidates who chose his question often scored very well with many gainingthe full 25 marks for their answers.

(a) Most candidates drew clear, well-labelled diagrams, correctly identifying the majorstructures in the flower.

(b) The descriptions of the events from pollination to fertilisation were often of a very goodstandard and those candidates who had carefully learned the material gained full credit.Some weaker candidates confused the terms and events so that pollen grains descendedthrough tubes etc.

(c) This experiment design was very variable with some candidates describing a sensibleexperiment in detail but others choosing the wrong experiment completely. Candidates whoscored well were able to describe the method of temperature control such as using arefrigerator to provide cool temperatures and an incubator or an oven to provide warmtemperatures. They also described using the same number of seeds in each temperature,grown on the same medium (such as cotton wool), soaked in the same volume of water. Theseeds were then left in these conditions for 2 days and the number of seeds germinating ateach temperature counted.

(d) Most candidates were able to give and explain two requirements for germination. Themost common answers given were oxygen for respiration and water to activate enzymes.

Question 5

This question was the most popular being answered by 87% of the candidates.

(a) Most candidates were able to give two substances required by a plant for photosynthesis.A few suggested sunlight which earned no credit. The second part of this item requiredcandidates to suggest why greenhouse crops grow faster. Some were able to describe howincreased temperature, artificial lighting and increasing carbon dioxide concentration wouldlead to an increased rate of photosynthesis. Other candidates suggested water availabilityand fertiliser provision but these were not credited as these can be provided outside agreenhouse.

(b) Many candidates were able to outline an experiment to show how varying the lightintensity provided to a water plant, such as Elodea, could alter the rate of photosynthesis.These accounts often gained full credit. Weaker responses used potted plants kept in darkor light conditions and then tested for starch. These responses earned limited credit. Theexperiment in which a light source is placed at various distances from a beaker containingpond weed and the rate of oxygen evolution is measured, was the best and simplest solutionto this question.

(c) Candidates who had learnt the composition of the molecules gained full marks.

(d) Many candidates answered this question well with some excellent answers gaining fullmarks.

NS

Question 6

This question was quite popular being answered by about 58% of the candidates.

(a) Most candidates who chose this question were able to list the appropriate terms from afood web.

(b) Some responses described the saphrophytic organisms as feeding on decayingorganisms. The examiners required a description of the digestion of dead or non livingorganic material to release elements or minerals.The experimental design item in this question required candidates to describe how varyingthe temperature might affect the growth of the fungus. The candidates who were able todescribe how the temperature could be varied and how the growth of the fungus could bemeasured earned credit. Providing a time scale and describing control variables led to fullmarks.

(c) Many responses earned high marks with candidates generally better able to describe therelationship for the bacteria of a sheep gut than for the bacteria in the root nodules of aleguminous plant.

(d) Responses to this item were very good with many gaining full marks for detailed andaccurate accounts.

Question 7

This was quite a popular question, being answered by about 57% of candidates.

(a) Candidates often described how diffusion and osmosis require a concentration gradientand some earned credit for describing both processes as passive.The differences between the two were often confused. Some gained credit for noting thatosmosis is the movement of water but many confused solvent and solution concentrations.Other responses earned credit for describing the presence of a selectively permeablemembrane in osmosis.

(b) The examiners were impressed by the knowledge shown by many candidates on thisitem.

(c) Here most candidates knew that Amoeba obtains its substances by diffusion with manycorrectly describing the large surface area to volume ratio as important.

(d) Candidates who described use of a potometer to measure the rate of water loss from acut leafy shoot could gain full credit. As with other items on the paper the examiners wereexpecting an account of how the humidity could be varied taking suitable measures overtime and controlling other variables. Credit was also given for suggesting that the resultswould show a reduced rate of transpiration as humidity increased.

NT

PAPER 2

Question 1

Most candidates appreciated that A was the trachea and that B was a bronchus. Bronchiolewas occasionally seen as the answer for B but was not credited. A surprising number failedto recognise C as a rib suggesting a degree of unfamiliarity with a labelled diagram of thethorax in section. In part (b), the better candidates understood that the position of thediaphragm would be lowered, the external intercostal muscles would relax, the ribcagewould be lowered, the volume of the thorax would be more and that the pressure in thethorax decreases during inhalation and increases during exhalation. The weaker studentstended to struggle with this latter observation. Candidates need to appreciate that the 3marks available in part (c) were for three distinct biological points. Most appreciated that alack of oxygen would be a factor but only the very best gained extra marks by makingreference to lack of glucose and respiration, and the build up of carbon dioxide or lactic acidand the consequent effect of low pH on enzyme function.

Question 2

Those candidates who looked carefully at the diagram understood that A and B had threechildren who were homozygous dominant. Genotype phrases in answer to part (b) were notcredited. The better candidates stated that F was female for one mark and an albino for thesecond mark. Once again, candidates are encouraged to look at the mark allocation as aguide to the detail required in their answers. In part (c), one mark was given for a squareshape and one mark was given for any shape that was half shaded. So, for example, a fullyshaded square was credited with one mark as was a half shaded circle. Most appreciatedthat the probability of D and P’s next child being a girl was a half and that the probability ofhaving a child with albinism was a quarter, but only the very best candidates understood thatthe probability of having a girl with albinism was an eighth.

Question 3

Most candidates were able to score highly on the graphical component of this question. Themost common errors involved joining the points with curved lines instead of straight lines asrequested, failure to draw lines to the origin, and failure to label each line in a way thatdistinguished the line for group A from the line for group B. Very few candidates madeplotting errors. In (a) (ii) most candidates recognised that more sulphate ions were absorbedby group A, but only the better candidates supported their description with reference to dataand also appreciated that the rate of uptake also differed. Part (a) (iii) was challenging formost candidates with only the stronger ones linking the role of oxygen in respiration toprovision of the energy for active uptake of ions. Part (b) was equally challenging as mostcandidates failed to appreciate that waterlogged soil would be lacking in the oxygen needed.Most candidates recalled that magnesium is needed for the manufacture of chlorophyll.

Question 4

Most candidates scored highly on this question. In part (a) a few failed to appreciate that theparts “not” found in typical animal cells was being asked for. In part (b) most studentscorrectly chose X and understood that water moved out of the cell. Only the bettercandidates explained why water moved out of the cell by making a correct reference to thewater concentration inside and outside the cell.

NU

Question 5

A precise answer was required in (a) (i). As such, glucose or oxygen were accepted, but airwas not. Most students recalled that carbon dioxide and water are substances produced byaerobic respiration. In part (b), the element nitrogen was required as the answer and mostcandidates were aware of this. Part (c) required candidates to apply biological principles toan unfamiliar situation and most successfully appreciated that there would be a temperaturerise that would kill or reduce the growth of the fungus by denaturing enzymes, and that theseevents would result in less mycoprotein. The structure of fungal hyphae is understood bymost candidates. The most difficulty was experienced when recalling that A represented anucleus, perhaps because students are not clear about the multinucleate nature of fungaltissue. This might also explain why some candidates thought that A represented a foodstorage molecule and then thought that D represented the nucleus. Part (c) was wellanswered by most students.

Question 6

Parts (a) and (b) were well answered with most candidates showing excellent knowledge ofthe carbon cycle. Part (c) was more challenging but most appreciated the impact ofurbanisation on plant populations and the consequent effects on plant photosynthesis andplant respiration.

Question 7

In part (a) most candidates interpreted the graphs to state that the age range for fish caughtin the area of over-fishing was 2 – 6 years, and that 8-year-old fish were most at risk of beingcaught in the area of less fishing. Similarly, most appreciated that young fish are smallenough to escape the nets. Those candidates who knew that legislation exists to bar thecapture of small fish were credited. Only the better candidates actually used the informationin the graphs to explain that the scarcity of older fish would result in a reduction inreproduction. Part (b) examined basic principles of fish farming but only the bettercandidates scored highly, appreciating that oxygen is important for respiration and thatbacterial decomposition of faeces may result in a fatal drop in the level of this important gas.Covering tanks with nets to prevent predation was a concept that half the candidatesseemed to appreciate.

Question 8

Candidates lost marks in part (a) by failing to name structures P and S precisely. The termsupper and lower epidermis were required, and the term epidermis alone was not credited.The recall of structure Q as the palisade mesophyll and structure R as the spongy mesophyllwas successfully achieved by most candidates. In part (b), the better candidates choseregion Q and explained that this region had more chloroplasts to absorb light and was nearto the upper surface to facilitate this process. Credit of one mark was given to thosecandidates who chose region R or region P providing they gave a sensible explanation. Nomarks were awarded to the few candidates who chose region S. While most students knowthe function of xylem, very few appreciate that the phloem transports sucrose. Answersstating food, sugars or glucose were not credited. Part (d) was well answered by mostcandidates and gave a spread of marks indicative of a question that discriminates betweenability levels.

NV

Question 9

Most candidates knew that mitosis and meiosis were the names of the types of cell division,but only the better candidates correctly chose mitosis for A and meiosis for B. In (a) (i), itwas apparent that the process of fertilisation is understood by the majority of students.However, while most students were aware that the haploid number for gametes is 23 andthat the diploid number for human cells is 46, very few were aware that red blood cells lack anucleus and as a result no chromosomes would be found.

Question 10

Part (a) discriminated very well with the most able candidates ticking the third, fourth andsixth boxes. Those who ticked all six, or five boxes, were awarded no marks. Those whoticked four boxes were marked according to the mark scheme and then had one markdeducted. Most appreciated the role of the glomerulus and Bowman’s capsule inultrafiltration. However, a large number of candidates believed that selective reabsorption ofglucose takes place at the loop of Henle. The correct response of the proximal convolutedtubule was seen less often.

BIOLOGY 7040, GRADE BOUNDARIES

Grade A B C D E

Lowest markfor award of

grade134 113 93 83 58

Note: Grade boundaries may vary from year to year and from subject to subject, dependingon the demands of the question paper.

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